A diagnosis of delayed motor development at one year made a significant independent contribution to IQ variance at age four, and was the best discriminator between retarded and normal children at that age. The purpose of this study is to define this condition more precisely in terms of specific development levels, and to examine some of its antecedents and longer-range outcomes at age seven. Factors investigated include maturitY at birth, phYsical growth, presence of neurological and other medical diagnoses at one and at seven years, socioeconomic status and education of the parents, and IQ at age seven.